1. Field of the Invention
The present invention relates generally to a telecommunications system and method for facilitating data exchanges between two users, particularly, to a telecommunication system and method for mediating data exchanges between user communication devices supporting different standards, and, more particularly, to a system and method for mediating data exchanges between two mobile subscribers operating under different and incompatible standards.
2. Background and Objects of the Present Invention
The evolution of wireless communication over the past century, since Guglielmo Marconi's 1897 demonstration of radio's ability to provide continuous contact with ships sailing the English Channel, has been remarkable. Since Marconi's discovery, new wireline and wireless communication methods, services and standards have been adopted by people throughout the world. This evolution has been accelerating, particularly over the last ten years, during which the mobile radio communications industry has grown by orders of magnitude, fueled by numerous technological advances that have made portable radio equipment smaller, cheaper and more reliable. The exponential growth of mobile telephony will continue to rise in the coming decades as well, as this wireless network interacts with and eventually overtakes the existing wireline networks.
This evolution in telephonic technology has also accelerated the growth of non-speech data communications, originally over the wireline, e.g., telecopy and facsimile, and now over the air. Furthermore, with the increasing use of computers, more and more individuals may, through their personal computer (PC) and a modem connection to an existing telephone network, communicate through the exchange of non-speech data. This phenomenon is best exemplified currently by the Internet. Although primarily confined to wireline systems today, the time for the transmission and exchange of non-speech data through mobile communications has arrived and is the subject of the present invention.
The interconnection of disparate systems, such as between a Public Land Mobile Network (PLMN) and a Public Switched Telephone Network (PSTN), i.e., a wireless and a wireline system, respectively, is common. As is understood by those skilled in this art, the interconnection and interoperation of such disparate systems, operating under very different standards and protocols, is difficult, and protocol translators are necessary to mediate communication.
One such protocol translator is a conventional interworking unit (IWU), which as its name suggests, mediates communication between different protocols within different systems. For example, through use of an IWU, a mobile subscriber in the PLMN may communicate with a user on the wireline PSTN, the IWU handling the protocol conversions necessary for the dialog.
In a Time Division Multiple Access (TDMA) digital standard now being used in Japan, named the Personal Digital Cellular (PDC) system, communication between mobile subscribers is performed using two operationally disparate speed levels, labeled low speed and high speed. Devices, such as modem adapters in, e.g., the PDC system, that are designed to operate at one speed, e.g., low, operate differently at the other and are technologically incompatible. Accordingly, two modem adapters at these different operational speeds cannot communicate and a protocol translator is required, such as the aforementioned IWU, to make the requisite protocol or standards conversions necessary for the mobiles' communication.
Although an IWU clearly may facilitate communication in a wireline or wireless environment, it is not always necessary to use one. For example, two mobile subscribers within a cellular system, such as PDC, both operating under the same standard, e.g., both low or both high speed, do not require the services of a translator and the subscribers may communicate directly. In particular, the modem or other adapters for each mobile subscriber in the communication understand each other. A translator such as the IWU is, however, necessary in a wireless system where the modem adapters used therein differ technologically, and failure to invoke the IWU in such instance results in communication failure and call disconnection.
Despite the aforedescribed standards mismatch problem, the IWU is generally not invoked during mobile-to-mobile calls within the PDC system, the system operating under the assumption that both subscribers utilize modems and other equipment with the same standard. Although this assumption may frequently be correct, when it is not and the standards of the modem adapters and other equipment of the two mobile subscribers are incompatible, communication is impossible without a protocol converter.
It is, accordingly, an object of the present invention to provide improved circuitry and methods to facilitate communication between equipment having different standards within a telecommunication system and avoid communication failures due to the aforedescribed incompatibilities.
It is also an object of the present invention to improve communications and avoid such failures through the exchange of standards information between the systems equipment, such as between the communications equipment of two mobile subscribers in a PDC system.
It is an additional object of the present invention to provide a method which invokes a protocol translator only when the protocols between subscribers' equipment mismatches.